Chronic obstructive pulmonary disease (COPD) has a profound impact on the lives of individuals who suffer from it. Participants with COPD are often caught in a downward spiral that goes from chronic airflow limitation to invalidity and poor quality of life. Exercise training is considered the key to successful pulmonary rehabilitation (PR) because it is responsible for much of the benefits associated with this intervention. However, despite current guidelines recommend high-intensity exercise training. the optimal exercise training protocol for PR participants has yet to be determined. Aims: The main goal of the proposed research project will be to determine the optimal exercise training protocol in PR. More specifically, the objectives will be to compare the effects of continuous high-intensity training (CT80), continuous training at the ventilatory threshold (CTVT), and interval training (IT) on various PR program outcomes and to compare participant compliance to the three training regimens. Methods: One hundred and twenty subjects will be recruited. Participants who meet the eligibility criteria and accept to participate in the study will be randomized to one of three groups: the CT80 group, the CTVT group, or the IT group. Session duration will be adjusted such that the total amount of work performed per session will be comparable between the three groups. Assessments will be made at baseline (week 0), at program completion (week 12), and one year after program start (year 1). The primary outcome measure will be short-term (12 weeks) change in exercise tolerance, as measured by the endurance time to constant-load cycling. Secondary outcome measures will include: long-term (1 year) change in exercise tolerance; short-term and long-term changes in functional status, psychological status, cognition, and health-related quality of life; average participant compliance to the target intensity throughout the 12-week program; and long-term adherence to exercise recommendations. Relevance: The proposed research will inform clinicians and scientists regarding which of the exercise training protocols currently used in PR is optimal for COPD participants by examining their short-term and long-term impact on physiological, functional, psychological, neuropsychological, behavioural and quality of life outcomes. For COPD participants, our findings have the potential to improve the effectiveness of a key intervention for the management of their disease.